PROJECT SUMMARY Progress in the genetics of aging field has demonstrated that, while chronological aging is unavoidable, biological aging is malleable, and targeting cellular processes to promote homeostasis is an alternative strategy to disease based approaches to alleviate the health burdens of old age. Both environmental conditions and conserved genetic pathways strongly influence the rate of physiological aging and organisms alter the rate at which they age and succumb to disease in response to external cues. The most potent example of this is dietary restriction (DR), reduced food intake without malnutrition, which slows aging in every organism tested thus far and protects against multiple chronic diseases, including cancer, cardiovascular disease and neurodegeneration. Our long-term objective is to elucidate how DR promotes healthy aging to allow the development of novel therapeutics to treat age-related disease. Maintaining a healthy proteome is essential for cellular survival and lifespan, and accordingly, reduced protein homeostasis underlies reduced fidelity of cellular processes with age. To date, interventions aimed towards maintaining a youthful proteome have focused on the two distal ends of the central dogma of DNA > RNA > Protein, targeting both transcriptional factors that regulate aging and homeostatic mechanisms that maintain correctly folded proteins. However, mRNA processing is a key intermediate step between DNA and proteins, yet RNA homeostasis and maintenance of pre-mRNA splicing efficiency have been largely ignored as a contributor to age-related dysfunction and organismal senescence. Our preliminary data demonstrate RNA splicing fidelity is a predictor of life expectancy, and that long-lived C. elegans on DR maintain a youthful splicing pattern compared to normal-lived control animals at the same chronological age. Demonstrating causality, we have identified components of the splicing machinery specifically required for DR longevity. Our central hypothesis is therefore that enhanced RNA homeostasis is required for DR longevity and interventions that promote splicing fidelity present novel therapeutic avenues for age-onset diseases. The objective of this application is to define the mechanism by which dietary restriction enhances splicing fidelity to increase longevity, in order to target RNA homeostasis to promote healthy aging. Collectively, we expect this work to be the first demonstration that RNA homeostasis decline is causal to organismal aging.